Fruiting body formation of the nivicolous myxomycete Badhamia alpina in moist chamber culture

Dehydration and self-cell cleaning by a single cell drives the formation of fruiting body of Lamproderma columbinum (Myxomycetes)

The noncellular complex structures of fruiting body produced by a multinucleate large plasmodium are the distinct character of Myxomycetes. Although the fruiting body distinguishes myxomycetes from other amoeboid single-cell organisms, it is unclear how such complex structures arise out of a single cell. The present study investigated the detailed process of fruiting body formation in Lamproderma columbinum, the type species of the genus Lamproderma, at the cellular level. A single cell excretes cellular waste and excess water during the formation of the fruiting body by controlling its shape, secreted materials, and organelle distribution. These excretion phenomena lead to the morphology of the mature fruiting body. The results of this study suggest that the structures of the L. columbinum fruiting body are involved not merely in spore dispersal but also in the process of dehydration and self-cell cleaning of the single cell for the next generation.

An exceptionally stable and widespread hydrated amorphous calcium carbonate precipitated by the dog vomit slime mold Fuligo septica (Myxogastria)

Biogenic amorphous calcium carbonate (ACC) is typically metastable and can rapidly transform through aging, dehydration, and/or heating to crystalline calcium carbonate. Gaining insight into its structure and properties is typically hampered by its tendency to crystallize over short time periods once isolated from the host organism, and also by the small quantities that are usually available for study. Here we describe an exceptionally stable hydrated ACC (HACC) precipitated by the cosmopolitan slime mold Fuligo septica (L.) F.H. Wigg. (1780). A single slime mold can precipitate up to a gram of HACC over the course of one night. Powder x-ray diffraction (XRD) patterns, transmission electron microscopy images, infrared absorption spectra, together with the lack of optical birefringence are consistent with an amorphous material. XRD simulations, supported by thermogravimetric and evolved gas analysis data, are consistent with an intimate association of organic matter with ~ 1-nm-sized ACC units that have monohydrocalcite- and calcite-like nano-structural properties. It is postulated that this association imparts the extreme stability of the slime mold HACC by inhibiting loss of H₂O and subsequent crystallization. The composition, structure, and thermal behavior of the HACC precipitated by F. septica collected over 8000 km apart and in markedly different environments, suggests a common structure, as well as similar biochemical and biomineralization mechanisms.

The life cycles of two species of Myxomycetes in Physarales, Physarum rigidum and Didymium squamulosum

Myxomycetes are eukaryotic microorganisms containing characteristics akin to both fungi and amoebae. They can complete their whole life cycles while being cultured on agar media, and under-laboratory conditions, which favors taxonomic, phylogenetic, and cytological researches. Here, we describe the life cycles of two such species: Didymium squamulosum collected from the field and Physarum rigidum cultured from moist chamber both belonging to the Order Physarales. Three per cent oat-agar media (OAM) was used to culture the plasmodia until they aggregated and were almost starved. Natural light was then applied to the plasmodia to induce fructification. Their life cycles share the same common stages, namely: spore, myxamoebae, swarm cell, plasmodia, and sporulation. In this study, we describe the morphogenesis from spore to spore of two species by differential interference contrast (DIC) and stereoscopic microscopies, as well as discuss the differences between the development of both species and interspecies. We found that the spore germination method of both species was the same. However, there were differences noted in time taken and fruiting body formation. Unlike P. rigidum, the species D. squamulosum did not require natural light stimulation. Moreover, the maturation process of both species had similar color transitions but exhibited distinct morphology in each developmental stage except during the swarm cell stage.